1. Field of the Invention
The present invention relates to a linear compressor, and in particular, to a suction guide noise reduction structure for a linear compressor which is capable of decreasing the specific volume of a sucked refrigerant gas, increasing the flow rate, and decreasing suction noise of the refrigerant gas by decreasing the amount of the refrigerant gas introduced from a suction opening of a hermetic vessel to be mixed with a high temperature refrigerant gas with which the hermetic vessel is filled.
2. Description of the Background Art
Generally, a compressor in a refrigerating cycle apparatus compresses refrigerant introduced from an evaporator, and then discharges it to a condenser in a high temperature and high pressure state.
In a conventional linear compressor, a piston is connected to a magnet assembly constituting an operator of a linear motor in place of a crankshaft thus to be integrally fixed to the magnet assembly. As the linear driving force of the motor is transferred to the piston, the piston linearly reciprocates in the cylinder to thus suck and compress refrigerant gas.
As shown in FIG. 1, a conventional compressor includes: a hermetic vessel 1 having a discharge opening (not shown) formed at one side and a suction opening la connected with a suction tube 2 at the other side; a frame 10 formed in a predetermined shape mounted inside the hermetic vessel 1; a cylinder 20 inserted into a through hole 3 formed through the central portion of the frame 10; an inner stator assembly 30 connected to an inner side of the frame 10 for constructing a linear motor and an outer stator assembly 31 connected to the inner side of the frame 10 at a predetermined interval; a magnet 32 disposed at a gap formed between the inner stator assembly 30 and the outer stator assembly 31; and a piston 40 inserted into the cylinder 20 and connected to a magnet assembly 33 connected with the magnet 32 for thereby reciprocating by the linear motion of the magnet 32.
A refrigerant flow path (F) through which refrigerant gas flows is formed inside the piston 40.
In addition, at one side of the cylinder 20, a cap shaped discharge cover 60 is connected to one side of the frame 10, wherein a discharge valve assembly 61 for opening and closing one side of the cylinder 20 is inserted into the discharge cover 60.
In addition, a suction valve 62 opened and closed according to the suction of refrigerant gas is connected to an end portion of the piston 40, and an oil feeder 70 for feeding oil in order to supply a sliding friction portion between elements with oil, is mounted at a lower portion of the frame 10.
In addition, a cover 50 is connected to the other side of the frame 10. And an inner resonance spring 51a inserted between a portion of the frame 10 disposed at the outer side of the cylinder 20 and an inner surface of the magnet assembly 33, and an outer resonance spring 51b inserted between an outer surface of the magnetic assembly 33 and an inner surface of the cover 50, are disposed at both sides of the magnet assembly 33 connected with the piston, so that they elastically support the piston 40.
Reference numeral 34 denotes a stator coil assembly of the linear motor.
The operation of the conventional linear compressor having the above-described structure is as follows.
When current is applied to the linear motor, the magnet 32 linearly reciprocates, and said linear motion is transferred to the piston 40 connected to the magnet assembly 33 so that the piston 40 linearly reciprocates in the cylinder 20.
A pressure difference is generated in the cylinder 20 by the linear motion of the piston 40. As refrigerant gas introduced into the hermetic vessel 1 via the suction opening 1a by this pressure difference in the cylinder 20, is introduced into the refrigerant flow path (F) formed inside the piston 40, sucking the refrigerant gas into the cylinder 20 via the suction valve 62, compressing the sucked refrigerant gas, and discharging the compressed refrigerant gas through the discharge valve assembly 61 and the discharge cover 60 are repeatedly performed.
In addition, the refrigerant gas of high temperature and high pressure is discharged through a tube connecting the discharge cover 60 and the discharge opening of the hermetic vessel 1 and then is introduced into a condenser (not shown). Thereafter, it is introduced into the condenser (not shown) constructing the refrigerating cycle apparatus, and then the refrigerant gas of low temperature and low pressure, which has passed again through the evaporator during a refrigerating cycle is introduced into the compressor.
Meanwhile, the compression efficiency in compressing the refrigerant gas, as the piston 40 reciprocates in the cylinder 20 is inversely proportional to the specific volume of the refrigerant gas. In order to decrease the specific volume of the refrigerant gas during the suction stroke, there has been a continuous effort to lower the temperature of the refrigerant gas when the refrigerant gas introduced into the suction opening 1a is introduced into the cylinder 20, because the temperature in the hermetic vessel 1 is high.
As an example of a conventional structure for preventing the heating of the refrigerant gas when the refrigerant gas is introduced into the cylinder 20 via the suction opening la of the hermetic vessel 1, as shown in FIG. 2, a suction induction tube 80 of which one side is extensively opened and which has a predetermined length in order for the refrigerant gas to be introduced into the suction opening 1a, is fixedly inserted into the refrigerant gas flow path (F) at a predetermined interval from the suction opening 1a. 
The suction induction tube 80 which moves together with the piston 40 is designed to be spaced apart from the suction opening 1a so that friction may not occur between an end portion of the suction induction tube 80 and an inner surface of the hermetic vessel 1 as the piston 40 reciprocates.
In the above-mentioned conventional linear compressor, however, there has been a problem in that since there must be a large interval between the suction induction tube 80 and the suction opening 1a, the sucked refrigerant gas is mixed with high temperature refrigerant gas in the hermetic vessel 1, thus increasing the specific volume of the refrigerant gas sucked into the cylinder.
In order to solve the above problem, as shown in FIG. 3, there is provided a structure in which the sucked refrigerant gas is introduced not into the hermetic vessel 1, but only into the cylinder 20 via a suction guide 81 and a suction induction tube 80xe2x80x2 by connecting an end portion of the suction induction tube 80xe2x80x2 inserted into the piston 40 and the suction opening 1a of the hermetic vessel 1 by means of the additional suction guide 81.
In the structure described above, the refrigerant gas is not mixed with the high temperature refrigerant gas with which the hermetic vessel is filled. However, there is a problem in that it is not easy to install the suction guide between the suction induction tube moving along with the piston and the hermetic vessel in a fixed state, and even after the installation, the suction guide may be easily damaged.
Meanwhile, as another example of the conventional linear compressor, as shown in FIG. 4, there is provided a structure in which a suction guide member 90 for guiding the suction of the refrigerant gas and decreasing noise during the suction of the refrigerant gas is mounted at the magnet assembly 33 and, inserted into the opening portion of the refrigerant flow path (F).
In detail, as shown in FIG. 5, in the suction guide member 90, a first small diameter portion 11 constituting a throat part is formed to be inserted into the refrigerant flow path (F) of the piston 40, a large diameter portion 12 of which one end communicates with the first small diameter portion 11 to form a resonance chamber is tightly formed at the rear end surface, that is, the opening portion of the piston 40, and a second small diameter portion 13 communicating with the other end of the large diameter portion 12 to thus form a suction opening is formed to be exposed to a refrigerant vent hole 2a of the cover 50.
In the conventional linear compressor thusly constructed, noise generated during the process of sucking the refrigerant gas via the suction valve 62 of the piston 40, is reduced by the acoustic characteristics while passing through the first small diameter portion 11 and large diameter portion 12 of the suction guide member 90.
Like reference numerals designate like composing elements illustrated in FIGS. 1 through 3. Thus, the description of such composing elements is omitted herein.
However, in order to increase the noise reduction amount of the suction guide member 90, the small diameter portion 11 has to be decreased or the effective volume (V1) of the resonance chamber has to be increased. In the conventional linear compressor described above in the case that the sectional area of the first small diameter portion 11 is too small, an intake loss of the refrigerant gas occurs to thereby degrade the compressor efficiency, and accordingly the decrease of the sectional area is limited. Since the suction guide member 90 is disposed at an inner space of the outer resonance spring 51b inside the cover 50 thus to reciprocate along with the piston 40, the increase of the effective volume (V1) of the resonance chamber is limited, thereby degrading both compression efficiency and noise reduction effect.
In addition, in the conventional linear compressor described above, the low temperature refrigerant introduced into the hermetic vessel 1 and into the cover 50 is mixed with high temperature refrigerant existing between the outside of the cover 50 and the hermetic vessel 1. Thus, there is a problem that the efficiency of the compressor is degraded.
More specifically, the suction guide member 90 integrally formed with the piston 40 has a large motion displacement, so that it has to maintain a considerable distance from the hermetic vessel 1. Thus, there is a problem that the high temperature refrigerant between the hermetic vessel 1 and the cover 50 is likely to be introduced into the suction guide member 90, and the efficiency of the compressor is degraded because the specific volume of the high temperature refrigerant is high.
Accordingly, it is an object of the present invention to provide a linear compressor which is capable of decreasing the specific volume of a sucked refrigerant gas by decreasing the amount of the refrigerant gas introduced from a suction opening of a hermetic vessel which is mixed with high temperature refrigerant gas with which the hermetic vessel is filled.
It is another object of the present invention to provide a linear compressor in which it is easy to install elements for guiding the suction of refrigerant gas.
It is still another object of the present invention to provide a linear compressor having at least one resonance chamber in order to substantially improve the noise reduction effect while maintaining the throat part of a suction guide member or the resonance chamber to be suitable for the efficiency of the compressor.
In order to achieve the above objects, there is provided a suction guide and noise reduction structure for a linear compressor including a hermetic vessel having a suction opening at one side thereof, a cylinder disposed inside the hermetic vessel, a piston inserted into the cylinder and having a refrigerant flow path formed inside, and a cover installed inside the hermetic vessel in the state of enclosing the cylinder and the piston and having a through opening at one side, which includes a suction guide tube connected with the through opening of the cover and fixed to the cover, said suction guide tube guiding refrigerant gas from the suction opening, and a suction induction tube fixedly connected with the refrigerant flow path at one end thereof and movably connected at the other end thereof with one end portion of the suction guide tube.